For a method of imaging a radiation image without using a silver halide in order to obtain the radiation image, a radiation image conversion panel in which a stimulable phosphor layer is provided on a support has been developed. Radiation energy depending on a radiation transmittance density at each part of an object can be accumulated with the radiation image conversion panel by exposing a stimulable phosphor layer to radiation passing through the object. The stimulable phosphor is subsequently excited on a time series basis with electromagnetic waves (stimulating light) such as visible light and infrared radiation to emit radiation energy accumulated in the stimulable phosphor as stimulated luminescence. The signal based on light intensity can be reproduced as a visible image on a recording material such as a silver halide photosensitized material or the like, and on a display device such as CRT or the like by obtaining an electrical signal via photoelectric conversion, for example. It is well known that superiority or inferiority of the radiation image conversion system using the radiation image conversion panel, is largely influenced by luminance of the stimulated luminescence of the panel and the luminescence uniformity of the panel, and specifically, these characteristics are largely influenced by the characteristics of the stimulable phosphor to be used.
A radiation image conversion panel fitted with a stimulable phosphor in which Eu is activated to alkali halide such as CsBr or the like as a base material has recently been proposed, and it is expected to enable improvement of X-ray conversion efficiency which used to be impossible by specifically utilizing Eu as an activator, whereby presumably, the radiation image conversion panel is largely to be utilized for a medical X-ray image diagnosis apparatus and so forth.
It is known that the radiation image conversion panel has a structure in which a protective layer (protective film) to cover a stimulable phosphor layer is provided to protect the stimulable phosphor layer from humidity, oxidation or the like after forming the stimulable phosphor layer on a support made of each kind of polymeric material, glass, metal or the like via evaporation of the above-described stimulable phosphor, as described in Japanese Patent O.P.I. Publication No. 2001-83299.
The radiation image conversion panel having such the structure is not favorable because of appearance of image defects in cases where dust larger than a pitch of an image reading apparatus installed in the X-ray image diagnosis apparatus adheres onto the stimulable phosphor layer. For this reason, as to the image reading apparatus installed in the X-ray image diagnosis apparatus, studied have been methods to remove dust attached on a protective layer (protective film) of a radiation image conversion panel thereof, and to reduce image defects. Known is a method of cleaning the surface of a protective layer (protective film) employing a rotatable brush roller brought into contact with the surface of the protective layer (protective film) and an apparatus by which dust removed with the brush roller is suctioned (refer to Patent Document 1, for example). Known is a method of cleaning the surface of a protective layer (protective film) by providing a flat brush brought into contact with the surface of the protective layer (protective film) in the conveyance path of the radiation image conversion panel (refer to Patent Document 2, for example).
Also known is a method of cleaning a stimulable phosphor layer to clean the surface of the foregoing stimulable phosphor layer employing a cleaning apparatus before sealing a stimulable phosphor plate having the stimulable phosphor layer provided on a substrate with a sealing film (refer to Patent Document 3, for example).
However, scratches are easily produced via concentration of stress into the protective layer provided on top of the stimulable phosphor layer, since the stimulable phosphor layer is in a delicate situation because of no phosphor coated with a binding agent or the like, and the surface of the stimulable phosphor layer is hard. Methods of touching the surface to be cleaned as described in Patent Documents 1 and 2 are not favorable since scratches are made on the surface of the stimulable phosphor layer. In addition, in the case of Patent Document 3, claggy dust can not be removed in use.
In such the situation, development of a method of cleaning a radiation image conversion panel exhibiting reduced surface scratch, image defects and image unevenness has been demanded.    Patent Document 1: Japanese Patent O.P.I. Publication No. 2001-337402.    Patent Document 2: Japanese Patent O.P.I. Publication No. 2001-321731.    Patent Document 3: Japanese Patent O.P.I. Publication No. 2006-329757.